Methods and system for simulated 3D videoconferencing

ABSTRACT

A system and method for manipulating images in a videoconferencing session provides users with a 3-D-like view of one or more presented sites, without the need for 3-D equipment. A plurality of cameras may record a room at a transmitting endpoint, and the receiving endpoint may select one of the received video streams based upon a point of view of a conferee at the receiving endpoint. The conferee at the receiving endpoint will thus experience a 3-D-like view of the presented site.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application claims priority to U.S. Provisional Application Ser.No. 61/452,270 entitled “Methods and System for Simulated 3DVideoconferencing” filed Mar. 14, 2011 and which is incorporated byreference in its entirety herein.

TECHNICAL FIELD

The present invention relates to the field of communication, and inparticular to the field of videoconferencing.

BACKGROUND ART

Videoconferencing enables individuals located remotely one from theother to conduct a face-to-face meeting. Videoconferencing may beexecuted by using audio and video telecommunications. A videoconferencemay be between as few as two sites (point-to-point), or between severalsites (multi-point). A conference site may include a single participant(user) or several participants (users). Videoconferencing may also beused to share documents, presentations, information, and the like.

Participants may take part in a videoconference via a videoconferencingendpoint (EP), for example. An endpoint (EP) may be a terminal on anetwork, for example. An endpoint may be capable of providing real-time,two-way, audio/visual/data communication with other terminals and/orwith a multipoint control unit (MCU). An endpoint (EP) may provideinformation/data in different forms, including audio; audio and video;data, audio, and video; etc. The terms “terminal,” “site,” and“endpoint” may be used interchangeably. In the present disclosure, theterm endpoint may be used as a representative term for above group.

An endpoint may comprise a display unit (screen), upon which videoimages from one or more remote sites may be displayed. Example endpointsinclude POLYCOM® VSX® and HDX® series endpoints, each available fromPolycom, Inc. (POLYCOM, VSX, and HDX are registered trademarks ofPolycom, Inc.) A videoconferencing endpoint may send audio, video,and/or data from a local site to one or more remote sites, and displayvideo and/or data received from the remote site(s) on its screen(display unit).

Video images displayed on a screen at an endpoint may be displayed in anarranged layout. A layout may include one or more segments fordisplaying video images. A segment may be a predefined portion of ascreen of a receiving endpoint that may be allocated to a video imagereceived from one of the sites participating in the videoconferencingsession. In a videoconference between two participants, a segment maycover the entire display area of the screens of the endpoints. In eachsite, the segment may display the video image received from the othersite.

An example of a video display mode in a videoconference between a localsite and multiple remote sites may be a switching mode. A switching modemay be such that video/data from only one of the remote sites isdisplayed on the local site's screen at a time. The displayed video maybe switched to video received from another site depending on thedynamics of the conference.

In contrast to the switching mode, in a continuous presence (CP)conference, a conferee (participant) at a local endpoint maysimultaneously observe several other conferees from different endpointsparticipating in the videoconference. Each site may be displayed in adifferent segment of the layout, which is displayed on the local screen.The segments may be the same size or of different sizes. Thecombinations of the sites displayed on a screen and their association tothe segments of the layout may vary among the different sites thatparticipate in the same session. Furthermore, in a continuous presencelayout, a received video image from a site may be scaled, up or down,and/or cropped in order to fit its allocated segment size. It should benoted that the terms “conferee,” “user,” and “participant” may be usedinterchangeably. In the present disclosure, the term conferee may beused as a representative term for above group.

An MCU may be used to manage a videoconference. An MCU is a conferencecontrolling entity that is typically located in a node of a network orin a terminal that receives several channels from endpoints and,according to certain criteria, processes audio and/or visual signals anddistributes them to a set of connected channels.

Exemplary MCUs include the MGC-100 and RMX 2000®, available from PolycomInc. (RMX 2000 is a registered trademark of Polycom, Inc.). Some MCUsmay be composed of two logical units: a media controller (MC) and amedia processor (MP). A more thorough definition of an endpoint and anMCU may be found in the International Telecommunication Union (“ITU”)standards, including the H.320, H.324, and H.323 standards. Additionalinformation regarding the ITU standards may be found at the ITU websitewww.itu.int.

In a CP videoconferencing session, the association between sites andsegments may be dynamically changed according to the activities takingpart in the conference. In some layouts, one of the segments may beallocated to a current speaker, for example. The other segments of thatlayout may be allocated to other sites that were selected as presentedsites or presented conferees. A current speaker may be selectedaccording to certain criteria, including having the highest audio signalstrength during a certain percentage of a monitoring period. The otherpresented sites, may include the image of the conferee that was theprevious speaker; the sites having audio energy above a certainthresholds; certain conferees required by management decisions to bevisible; etc.

In a conventional CP videoconference, each layout is associated with avideo output port of an MCU. A conventional video output port maycomprise a CP image builder and an encoder. A conventional CP imagebuilder may obtain decoded video images of each one of the presentedsites. The CP image builder may scale and/or crop the decoded videoimages to a required size of a segment in which the image will bepresented. The CP image builder may further write the scaled image in aCP frame memory in a location that is associated with the location ofthe segment in the layout. When the CP frame memory is completed withall the presented images located in their associated segments, the CPimage may be read from the CP frame memory by the encoder.

The encoder may encode the CP image. The encoded and/or compressed CPvideo image may be sent toward the endpoint of the relevant conferee. Aframe memory module may employ two or more frame memories, for example,a currently encoded frame memory and a next frame memory. The memorymodule may alternately store and output video of consecutive frames.Conventional output ports of an MCU are well known in the art and aredescribed in a plurality of patents and patent applications. A readerwho wishes to learn more about a conventional output port is invited toread U.S. Pat. No. 6,300,973, for example, the content of which isincorporated herein by reference in its entirety.

A user's experience of videoconference is typically limited to one ormore high-resolution two-dimensional displays. Although 3D (3-dimension)technologies have become more and more popular in other differentfields, such as movies, media entertainment, etc., obstacles haveprevented the 3D technology from being implemented by thevideoconference industry. These obstacles include the need to wearspecial 3D glasses and the use of expensive cameras and displays.Creation of holograms may require special screens, cameras, and hardwarethat are very expensive, etc. Therefore, it is not realistic to expectconventional videoconferencing users to pay such high costs. Nor is itrealistic to expect conventional videoconferencing users to sit in avideoconference wearing 3D glasses, which would be visible to otherconferees.

Furthermore, many companies have invested in a conventional 2D videoconferencing infrastructure. Those companies would like to keep theircapital investment in their current video conferencing infrastructurethat does not support current existing 3D video conferencing techniques.

The above-described deficiencies in videoconferencing do not limit thescope of the inventive concepts of the present disclosure in any manner.The deficiencies are presented for illustration only.

SUMMARY OF INVENTION

The below disclosed embodiments provide a novel system and method formanipulating a video image in videoconference such that a user mayexperience a 3D-like view of one or more presented sites. The disclosedexemplary embodiments do not require 3D cameras, 3D screens, 3D glasses,or hologram display hardware. On the contrary, the disclosed embodimentsmay utilize conventional 2D video cameras and conventional 2D videoscreens to create a 3D-like view of one or more presented sites.

In one embodiment, a transmitting endpoint in a site may comprise two ormore video cameras, each of which may record the room of the site from adifferent angle. The transmitting endpoint may encode each video imageand send the encoded streams to an MCU.

At the MCU, each of the received video streams from a plurality ofconferees is transferred toward an associated input video port. Inaddition to the conventional components of an input video port, an inputvideo port may comprise a conferee-point-of-view detector (CPOVD). TheCPOVD may detect the angle at which the conferee looks at the screen andat which region of the screen the conferee is looking. The CPOVD maysend the detected information toward a controller of the MCU.

As long as the video image of a transmitting endpoint, which has two ormore cameras, is embedded in the video image that is sent toward one ormore receiving endpoints, the controller may periodically sample thestored information regarding the received conferee's point-of-viewdirection. Once a change in the viewer's point of view has beendetected, the controller may determine whether to continue using thevideo streams from the currently chosen camera, to select a video streamreceived from another camera of that transmitting endpoint, etc.

The viewer, in the receiving endpoint, will experience a 3D-like view ofthe presented sites. This experience may be affected by the number andlocation of the cameras in the transmitting endpoint. To enhance theexperience, more cameras may be placed and along an arc wherein thecenter of the arc is located near to or on the centerline of the displayat the transmitting site. Furthermore, the accuracy of theviewer-point-of-view detector may also affect the experience of theuser.

Other different techniques may be used to enhance the viewer'sexperience. Exemplary techniques include using a “sliding window,” forexample. The sliding window imitates the effect of controlling the farend camera such as move left, right, up and down. In some embodiments,the movement of the receiving conferee's gaze may be used as a remotecamera panning left or right, tilting up or down or zooming in or out.In some embodiments, the video received from the remote location may becropped to a window that is presented on screen and slides along thevideo image. For example, if the conferee gaze detector indicates thatthe gaze of the conferee points at the most left side of the screen, theeffect on the screen may resemble a panning left of the remote camera,although in this embodiment only the presented window is sliding to theleft and the remote camera is not panning left. Once the conferee pointof view is locked on the area in which the conferee is interested, thewindow may slide until it will eventually stop. In the above embodiment,the stopping point may be the point in which the conferee is staring tothe center of the conferee's screen.

The present disclosure is not limited to providing a 3D-like view ofonly one site. One or more sites may comprise a plurality of cameras.The number of segments displayed in a layout on a conferee screen aswell as the conferee's screen size may affect the 3D-like experience.

These and other aspects of the disclosure will be apparent in view ofthe attached figures and detailed description. The foregoing summary isnot intended to summarize each potential embodiment or every aspect ofthe present invention, and other features and advantages of the presentinvention will become apparent upon reading the following detaileddescription of the embodiments with the accompanying drawings andappended claims.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate an implementation of apparatusand methods consistent with the present invention and, together with thedetailed description, serve to explain advantages and principlesconsistent with the invention. In the drawings,

FIG. 1 is a block diagram illustrating relevant elements of a portion ofa multimedia multipoint videoconferencing system according to oneembodiment.

FIGS. 2 a-2 c illustrate different instances during a video conferencingsession, in which a conferee has different viewpoint in each instance.

FIG. 3 is a block diagram illustrating relevant elements of portions ofa transmitting site according to one embodiment.

FIG. 4 is a block diagram illustrating relevant elements of an exemplaryMCU, according to one embodiment.

FIG. 5 is a flowchart illustrating relevant actions of a process forselecting a camera based on conferee point of view, according to oneembodiment.

DESCRIPTION OF EMBODIMENTS

In the following description, for purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of the invention. It will be apparent, however, to oneskilled in the art that the invention may be practiced without thesespecific details. In other instances, structure and devices are shown inblock diagram form in order to avoid obscuring the invention. Referencesto numbers without subscripts or suffixes are understood to referenceall instance of subscripts and suffixes corresponding to the referencednumber. Moreover, the language used in this disclosure has beenprincipally selected for readability and instructional purposes, and maynot have been selected to delineate or circumscribe the inventivesubject matter, resort to the claims being necessary to determine suchinventive subject matter. Reference in the specification to “oneembodiment” or to “an embodiment” means that a particular feature,structure, or characteristic described in connection with theembodiments is included in at least one embodiment of the invention, andmultiple references to “one embodiment” or “an embodiment” should not beunderstood as necessarily all referring to the same embodiment.

Although some of the following description is written in terms thatrelate to software or firmware, embodiments may implement the featuresand functionality described herein in software, firmware, or hardware asdesired, including any combination of software, firmware, and hardware.In the following description, the words “unit,” “element,” “module” and“logical module” may be used interchangeably. Anything designated as aunit or module may be a stand-alone unit or a specialized or integratedmodule. A unit or a module may be modular or have modular aspectsallowing it to be easily removed and replaced with another similar unitor module. Each unit or module may be any one of, or any combination of,software, hardware, and/or firmware, ultimately resulting in one or moreprocessors programmed to execute the functionality ascribed to the unitor module. Additionally, multiple modules of the same or different typesmay be implemented by a single processor. Software of a logical modulemay be embodied on a computer readable medium such as a read/write harddisc, CDROM, Flash memory, ROM, or other memory or storage, etc. Inorder to execute a certain task a software program may be loaded to anappropriate processor as needed.

In the description and claims of the present disclosure, “comprise,”“include,” “have,” and conjugates thereof are used to indicate that theobject or objects of the verb are not necessarily a complete listing ofmembers, components, elements, or parts of the subject or subjects ofthe verb.

FIG. 1 illustrates elements of an exemplary multimedia multipointconferencing system 100 according to one embodiment. System 100 mayinclude a network 110, one or more multipoint control units (MCU) 120,and a plurality of endpoints in different sites 130 a-n. Network 110 maybe a packet switched network, a circuit switched network or anycombination of the two, for example. The multimedia communication overthe network may be based on a communication protocol, including H.320,H.323, SIP, etc.

MCU 120 and endpoints 130 a-n may be adapted to operate according tovarious embodiments to improve the experience of a conferee looking at aCP video image of a multipoint video conference. In embodimentsimplementing a centralized architecture, MCU 120 may be adapted toperform the automatic display adaptation methods described herein.Alternatively, in a distributed architecture, endpoints 130 a-n with MCU120 may be adapted to perform the automatic display adaptation methods.More information about the operation of MCU 120 and endpoints 130 a-naccording to various embodiments is disclosed below.

FIGS. 2 a-2 c illustrate different instances during a video conferencingsession in which a conferee 204 has a different viewpoint in eachinstance. In FIG. 2 a, conferee 204 looks at the center along theperpendicular 210 of the two-dimensional screen 202 of the conferee'sEP. In FIG. 2 b, the head of conferee 204 is rotated to the right sideof the screen 202 and creates an angle 216 of +A degrees between theface (the nose) of the conferee and the perpendicular 210 to the screen.In FIG. 2 c, the head of conferee 204 is rotated to the left side of thescreen 202 and creates an angle 216 of −a degrees between the face (thenose) of the conferee and the perpendicular 210 to the screen.

FIG. 3 illustrates a block diagram with relevant elements of portions ofa transmitting site 300 according to one embodiment. Transmitting site300 may be a meeting room having a table 310, a plurality of chairs 312,and a videoconferencing endpoint 330 having a plurality of video cameras320, 322, and 324. The plurality of cameras may be located in ahorizontal plane above the screen of the EP 330 along a virtual arc.Each camera captures the table 310 and the conferees along the tablefrom a different angle simulating a different head position of aconferee that receives a video stream from the meeting room 300. Each ofthe video cameras 320, 322, and 324 creates and delivers a stream ofvideo images to the endpoint 330. The endpoint 330 compresses the threevideo streams and sends the compressed video streams toward an MCU 120that conducts the video conferencing session. Compressing the threevideo streams may be done in a single encoder that complies with thecompression standard H.264 MVC, for example. Other endpoints may usethree separate encoders and may send three separate compressed videostreams, one for each of cameras 320, 322, and 324.

FIG. 4 illustrates an MCU 400, which is capable of dynamically andautomatically switching between a plurality of streams of video images.The plurality of streams received from a plurality of video cameras 320,322, and 324 associated with an EP 330 located in a first site 300. Theswitching at the MCU 400 may be done based on the gaze of an observer,located in a second site and receives the selected video image sent fromthe first site via the MCU 400. MCU 400 may comprise a network interfacemodule (NI) 420, an audio module 430, a control module (CM) 440 and avideo module 450. The control module 440 may further comprise a cameraselector controller (CSC) 442. The network interface module 420 mayreceive communication from a plurality of endpoints 130 a-n via network110. Network interface 420 may process the communication according toone or more communication standards, including H.320, H.323, SIP, etc.Network interface 420 may also process the communication according toone or more compression standards, including H.261, H.263, H.264, H.264MVC, G.711, G.722, MPEG, etc. In addition, network interface 420 mayreceive and transmit control and data information to/from other MCUs andendpoints. More information concerning the communication betweenendpoint and the MCU over network 110 and information describingsignaling, control, compression, and setting a video call may be foundin the international telecommunication union (ITU) standards H.320,H.321, H.323, H.261, H.263, H.264, G.711, G.722, and MPEG etc.

Network interface module 420 may multiplex/de-multiplex the differentsignals, media and/or “signaling and control” that are communicatedbetween the endpoints and the MCU. The compressed audio signals may betransferred to and from the audio module 430. The compressed videosignals may be transferred to and from the video module 450. The“control and signaling” signals may be transferred to and from controlmodule 440. Furthermore, if a distributed architecture is used, networkinterface module 420 may be capable of handling automatic and dynamicgaze related information that is transferred from the endpoints 130 a-ntoward the control module 440.

In one distributed architecture embodiment the automatic and dynamicgaze detection information is sent from an EP 130 to MCU 400. The gazedetection information may be sent from the EP 130 as a part of apredefined header of an RTP (Real-Transport Protocol) packet. NI 420 maybe adapted to process the predefine header and to transfer the gazedetection information to the CM 440. The gaze detection information mayinclude the angle ±a (216, 218) of the nose of the conferee from theperpendicular 210. In another embodiment, the information about the gazeof the conferee may be expresses by the location of the conferee's nose,in pixels (W;H) along the width ‘W’ axis, and height ‘H’ axis of thevideo image received from that conferee's EP, for example. In someembodiments, the gaze may be expressed in number of pixels in pixels(W;H) from the top left corner of the image.

In yet another distributed architecture embodiment, the EP may sendinformation regarding the gaze of its conferee over the audio signalusing dual-tone multi-frequency signaling (DTMF). In such an embodiment,the NI 420 processes the received signals and sends the compressedaudio, carrying the DTMF signal toward the audio module 430. The audiomodule 430 decompresses the audio signal, decodes the DTMF information,and transfers the Gaze information toward the CM 440. In yet anotherdistributed architecture embodiment, the EP 130 may send informationregarding the gaze of its conferee via out of band connection. The outof band connection may be carried over an Internet Protocol (IP)network, for example. In such embodiment, the NI 420 may process thereceived IP packets, carried over an IP connection and sends the Gazeinformation toward the CM 440.

Audio module 430 may receive, via network interface 420 compressed audiostreams from the plurality of endpoint 130 a-n. The audio module 430 maydecode the compressed audio streams, analyze the decoded streams, selectcertain streams, and mix the selected streams. The mixed stream may becompressed and the compressed audio stream may be sent to the networkinterface 420, which sends the compressed audio streams to the differentendpoints 130 a-n. Audio streams that are sent to different endpointsmay be different. For example, the audio stream may be formattedaccording to a different communication standard and according to theneeds of the individual endpoint. The Audio stream may not include thevoice of the user associated with the endpoint to which the audio streamis sent. However, the voice of this user may be included in all otheraudio streams.

In some embodiments, the audio module 430 may be adapted to analyze thedecoded audio signals received from the endpoints, and decodes the DTMFsignals for retrieving information regarding the gaze of the conferee'swhose audio signal was processed. The gaze information may betransferred to the control module 440. In some embodiments, two or moremicrophones may be used in a certain site.

Video module 450 may receive compressed video streams from the pluralityof endpoints 130 a-n, which are sent toward the MCU 400 via network 110and processed by network interface (NI) 420. Video module 450 may createone or more compressed CP video images according to one or more layoutsthat are associated with one or more conferences currently beingconducted by the MCU 400. A video module 450 may have a plurality ofinput modules 451 a-c, a plurality of output modules 455 a-c and a videocommon interface 454. Each input module 451 a-c may be associated withan endpoint. Each output module 455 a-c may be associated with one ormore endpoints.

Input module 451 a-c may include among other elements a decoder 452 anda Conferee's-Point-of-View Detector (CPOVD) 453. CPOVD 453 may be asub-module of input modules 451 a-c, or in an alternate embodiment,CPOVD 453 may be a sub-module of video module 450. An input module 451a-c may be associated with an endpoint and may process a pluralitystreams of compressed video images received from plurality of videocameras 320-324 that are connected to the associated endpoint 330. Thedecoder 452 may receive the plurality of compressed video streams, whichmay comprise three streams for example, from an associated endpoint anddecode the compressed video stream according the compression standardH.264 MVC into three decoded video data images, each decoded imagereceived from one of the three cameras. The ITU H264 MVC standard is amulti-view-video-coding standard, which enables the transmittingendpoint to broadcast multiple video streams from the two or morecameras. Each decoded image may be stored in a decoder frame memory fromwhich it is transferred toward one or more output modules 455 a-c viacommon interface 454. The common interface 454 may be a TDM bus, packetbased bus (such as an ATM bus, IP bus), serial bus, parallel bus,connection switching, shared memory, direct connection, or any varietyof these.

In an alternate embodiment in which H.264 MVC is not used, an inputmodule may be associated with one of the cameras 320-324 of itsassociated endpoint 330. Thus, endpoint 330 may be associated with threeinput modules 451.

The MCU receives from a plurality of endpoints a plurality of compressedvideo streams. Some of the endpoints may send compressed video streamsreceived from its two or more video cameras using the ITU H.264 MVCstandard, while other endpoints may send a compressed video streamreceived from a single video camera.

In one embodiment, each of the endpoints 330 may comprise a CPOVD 453that receives the video input data from an endpoint camera, processesthe received data, and defines the direction in which the conferee islooking The conferee point of view information may then be sent to theMCU from the endpoint. The information may be sent in-band, inassociation with the compressed video stream, as part of a packet'sheaders. Alternatively, the information may be sent out of band over aseparate connection between the endpoint and the MCU, over an InternetProtocol (IP) connection, for example.

In one embodiment, the decoded data stored in the frame memory, which isassociated with the central camera 322 may be sampled by the CPOVD 453.CPOVD 453 may be adapted to analyze the video image received from thecentral camera and to detect the gaze of the conferee that uses theassociated EP 330. A CPOVD 453 may process the decoded image; identifythe nose of the conferee; and determine the location of the nosecompared to the perpendicular 210 to the screen, or the center of thescreen. Detecting the nose may be implemented by an image-processingalgorithm that identifies the two eyes and the nose in the center. In asite that has only one camera, the images from the single camera areprocessed instead of the video of the central camera.

In some embodiments of an MCU 400, a central CPOVD 453 may be used. Sucha central CPOVD 453 may obtain the decoded video from each one of theinput video ports, in parallel or in serial. Such a CPOVD 453 mayprocess the obtained decoded video and determine the gaze angle of theconferee. The detected gaze angle may be used for selecting theappropriate camera.

In one embodiment, an MCU 400 may use a learning period for learning theproperties of an organ of the conferee's face, such as a nose, an eye(left, right or both), etc. the term nose may be used as arepresentative term for such an organ. In addition for learning the areaaround the nose, the CPOVD 453 may learn the topology of the gaze(represented by the nose, for example) in relation to the video imagereceived from the center camera and the screen of the endpoint. Thelearning period may begin upon receiving a request from a conferee tojoin the conference. During the learning period, the MCU 400 may presentthe self-image of the conferee, which is received from the centercamera, over the entire screen of the conferee's endpoint. In additionto the self image, the MCU 400 may present above the self image threepoints (colored area, a circles, for example) along a virtual horizontalline starting from left to right in the middle of the height of thescreen. In other embodiment, five points may be presented on the screen,one in the center of the screen, and one at the center of each quarterof the screen (i.e., the center of the top left quarter, the center ofthe top right quarter, the center of the bottom left and the center ofthe bottom right quarter).

The MCU 400, by using an interactive-video-control-human interface mayplace a cursor on the screen and prompt the conferee to look at thecenter point on the screen and to place the cursor on the conferee'snose. Prompting the conferee may be done by an Interactive VoiceResponse (IVR) or by presenting text instructions over the screen. Afterclicking on the cursor, the MCU 400 may collect information on thelocation of the nose and the properties in a certain area around thenose while the conferee looks at the center point. The process may berepeated for each of the colored points. In some embodiments, two ormore points may be used in each side of the screen. Theinteractive-video-control-human interface is disclosed in U.S. Pat. No.7,542,068, the content of which is Incorporated herein by reference inits entirety. At this point of time the CPOVD 453 has information on thelocation (in pixels from the top left corner of the image) of theconferee's nose in the video image received from the conferee's centercamera 322 when the conferee looks at the center of the screen and atthe center of each quarter of the screen. In addition, the CPOVD 453 hasinformation on the properties of the area around the nose in eachposition. This information may be processed for use as filters to definethe gaze of the conferee during the video session.

In yet another embodiment, the CPOVD 453 may implement a gaze detector.Gaze detection methods are well known in the art of image processing.There are a plurality of articles that describe different method of gazedetection. Some of them use a wearable device such as magnetic elements,RF receivers, and or transmitters, etc., others uses a dedicated camerafor tracking and capturing the user's eyes, others just run imageprocessing algorithms that identify the user's gaze, etc. a CPOVD 453may use a commercial gaze detector. Example commercial gaze detectionsystems include SMI RED systems RED, RED 250, and RED 500, manufacturedby SensoMotoric Instruments GmbH (SMI) from Teltow Germany. Other gazedetection systems use the red-eye effect by using a near infraredlighting source. Gaze detection techniques are known to the art and willnot be further discussed herein.

Various embodiments may implement different techniques of gazedetection. Some embodiments may use near infrared (NIR) lighting andanalyzing the received video image looking for the red-eye effect on theimage. Other embodiments may implement image-processing methods lookingfor changes in the gaze direction. The information about the currentgaze direction of the conferee in a receiving endpoint, or changes inthe gaze directions may be utilized for controlling the video imagereceived from a transmitting endpoint such that the transmitted image isadapted to the gaze of the receiving endpoint.

In some embodiments, if two or more conferees share the same site andthe same endpoint, one of them may be selected as the one to whom thegaze detector will respond. The selection of the conferee may be doneautomatically in one embodiment. The selection criteria that may be usedmay include the conferee that sits in the head of the table, theconferee that sits in the center of the group of conferees, the confereethat sits closest to the camera, etc. In other embodiments, the confereemay be selected manually during the beginning of the conference session,for example when in the learning mode.

From time to time, periodically, and/or upon receiving a command fromthe CSC 442, the CPOVD 453 may sample a captured frame of the decodedvideo. The CPOVD may analyze the sampled image and identify thedirection of the conferee's gaze. The CPOVD 453 may output the gazedetected information to the CSC 442 via control line 444.

The received conferee's point of view information may be stored at theMCU controller. This information may be used for controlling a videooutput port that has been assigned to that received conferee. When theMCU controller determines that video image received from a transmittingendpoint having two or more cameras is to be transmitted toward theendpoint of the received conferee, then the information regarding thereceived conferee's point of view may be used for selecting anappropriate video stream of the video streams received from the two ormore video cameras of the transmitting endpoint.

In some embodiments, the CPOVD 453 may deliver parameters according tothe location of the nose. The nose represents the center of the gaze ofthe conferee. The location may be in pixels. In some embodiments of thevideo module 450, a single CPOVD 453 may be used. Such a CPOVD 453 maybe a separate module external to the input module 451 a-c. In suchembodiment, the CPOVD 453 may obtain from the common interface 454 adecoded video frame received from one of the input modules 451 a-c,process it, and deliver gaze information to the CSC 442. Then, the CPOVD453 may obtain decoded frame received from a next input module 451 a-c,process it, deliver gaze information and may continue to the followinginput module, looping repeatedly. In a distributed architecture, a CPOVD453 may be located in an endpoint 330 and may process the video datagenerated by its central video camera 322. More information about theoperation of a CPOVD 453 is discussed below in conjunction with FIG. 5.

Among other elements, an exemplary output module 455 a-c may include aneditor 456 and an encoder 458. Editor 456 may get decoded data ofselected video images from the common interface 454 to be composed intoa CP image created by the output module 455. The editor 456 may scale,crop, and place the video data of each conferee into an editor framememory according to the location and the size of the image in the layoutassociated with the composed video of the CP image. Editor 456 andencoder 458 may each be considered as modules, or as sub-modules ofoutput modules 455 a-c.

When the editor frame memory is ready with all the selected conferee'simages, the data in the frame memory is ready to be encoded by encoder458 and sent toward its associated endpoint. The editor 456 may beconfigured to collect the decoded video images received from a pluralityof endpoints (video input modules 451 a-c), to build the frames of theCP video images based on layout instructions received from the CM 440regarding each video image, and send the composed CP video image towarda display unit of the endpoint.

Depending on the current layout that is transmitted toward the receivedconferee, the conferee's video output port may arrange the selectedvideo stream in a segment of a CP video image or as a switching videoimage and send it toward the receiving endpoint. In some embodiments,the 3D imitation may be limited to images that are displayed in asegment bigger than a certain size, a quarter of a screen for example.

Additional functions that may be included in the video module 450 aredescribed in U.S. patent application Ser. No. 10/144,561; U.S. Pat. No.6,100,973; and International App. Serial No. PCT/IL01/00757, thecontents of which are incorporated herein by reference. In a distributedarchitecture, an endpoint may include an editor 456. In such embodiment,the editor 456 may be located after a decoder of the endpoint.

In addition to the operation of an editor 456 in an output module,editor 456 may be able to adapt the video image presented in at leastone segment of the CP video image to the gaze of the conferee that isassociated with that editor 456 and receives that CP video image. Thisconferee is referred to as the receiving conferee. An exemplaryembodiment of an editor 456 may adapt the video image in the currentspeaker segment to the gaze of the receiving conferee looking at thespeaker image in the CP video image. To do so, the editor 456 may obtainfrom CSC 442 information about which one of the three video cameras320-324 of the endpoint of the current speaker fits the gaze of thereceiving conferee. During a transition from one camera to anothercamera of the same endpoint, different techniques may be used toovercome transition digital artifacts caused by the difference betweenthe positions of the cameras, including morphing techniques forsmoothing the transition. The morphing technique may provide aperception of a smooth transition. Morphing techniques are well known inthe video processing arts and have been used for more than twenty years.Other techniques that may be used include fading-in effects, fading-outeffects, etc.

Furthermore, in order to avoid jumping from one camera to the other andvice versa, an embodiment may have an overlap between two adjacentcameras and may use hysteresis in the decision thresholds for selectinga camera based on the receiving conferee's point of view. Consequently,the changing point from a right camera to a left camera may be otherthan the changing point from the left camera to the right one.

In addition, some embodiments after changing the selected camera, a timedelay may be implemented for a certain period, for example a fewseconds, in which the selected video camera is not changed again.

Control module 440 may be a logical unit that controls the operation ofthe MCU 400 and conducts the conference session. In addition toconventional operation of a typical MCU, MCU 400 according to variousembodiments may be capable of additional functionality as result ofhaving the control module 440. Control module 440 may include aCamera-Selector Controller (CSC) 442. In one embodiment, a CSC 442 maycontrol a plurality of video output modules 455 a-c. In otherembodiments, each of a plurality of CSC 442 controls an output module455 a-c. Per each output module 455, a CSC 442 may receive gazeinformation of the conferee associated with the EP that is associatedwith that output module 455. The gaze information may include the viewangle ±a 216, 218 of the conferee from the perpendicular 210 to theconferee's screen. In other embodiments, the gaze information may be thecoordinates (W;H, Width; Height) of the nose of the conferees in pixelsalong the width axis (W) and the height (H) axis of the conferee's selfimage received from the center camera 322 of the conferee's EP 330, etc.

In other embodiments, an MCU for media relay video conferencing (a mediarelay MCU or MRM) may use a distributed architecture as describedherein. In such an architecture, the endpoints 330 may comprise the gazedetector and the editor. The gaze detector may process the video imagereceived from one of the cameras 320, 322, and 324 of the endpoint 330to define the gaze of the conferee and transfer the gaze informationtoward the CSC 442 that is located in the MRM. The editor may select oneof the decoded streams from the endpoint decoder 452 that were receivedfrom a transmitting endpoint to which the gaze of the conferee pointed,according to instructions obtained from the CSC 442, and embed theselected stream in a CP video image that may be presented on theendpoint display unit. A reader who wishes to learn more about mediarelay video conferencing and MRM is invited to read US PatentApplication Publication No. 2010/0194847, the content of which isincorporated herein by reference.

After collecting the information on the conferee's gaze and the layoutthat is currently presented to that conferee, the CSC 442 may determinethe segment at which the conferee is looking Then, CSC 442 may determinewhich camera (320, 322, or 324) of the endpoint 330 that is associatedwith this segment matches the direction of the conferee's gaze. If theconferee looks to the left side of the segment, then camera 320 may beselected. If the conferee looks to the right side of the segment, thencamera 324 may be selected, and if to the center of the segment thencamera 322 may be selected. Information on the selected camera may betransferred to the editor 456 of the output module 455 that is assignedto that conferee. The information may include information how to obtainthe decoded data from the common interface 454 and instead of eachstream to place this image in the CP video image. More information onCSC is disclosed below in conjunction with FIG. 5.

In some embodiments, a single CSC 442 may control a plurality of editors456. In other embodiments, a plurality of CSCs 442 each control one ofthe plurality of editors 456. The CSC 442 may calculate the scaling,cropping, and movement when moving from one camera to another.

Based on this information, the editor 456 starts the replacing process.In some embodiments, replacing images from two different cameras in thesame room may take few frames in order to smooth the transition. Anexemplary embodiment may use a fading technique in which the old imageis faded while the image from the selected camera is increased. Otherembodiment may use a morphing technique to provide a perception of asmooth transition, etc.

FIG. 5 is a flowchart illustrating relevant actions of process 500.Process 500 may be implemented by a CPOVD 453 for defining the gaze ofthe conferee that is associated with that CPOVD 453 and selecting acamera, in a second room, based on the conferee's s point of view. Inthis embodiment, the conferee resides at a first site, and is referredas a first conferee, while the cameras (320, 322, and 324) are locatedat a second site 300. In one embodiment, process 500 may change camerasonly if the first conferee looks at the segment of the current speaker.Other embodiments may switch between cameras even if the first confereelooks at a segment other than the segment of current speaker in the CPvideo image.

The process may be initiated in block 502 by CSC 442 when the firstconferee joins the conference. Upon initiation in block 502, a learningperiod may be executed by the CPU of the CPOVD in block 504. During thelearning period in block 504, the CPOVD 453 may learn the topology ofthe first site as it is reflected in a video image received from acamera in the first site. The camera may be the center camera if theendpoint in the first room has three cameras; otherwise, where only onecamera exists at the first site, the camera may be the only camera usedin the first site. Learning the topology may include identifying thelocation of the first conferee in the self-image, associating the gazeas it is expressed on the image with a location on the screen on whichthe conferee looks, etc. Learning the topology may be done automaticallyby prompting the conferee to look at a different location on the screenand determining the conferee's gaze at each time. In some embodiments,learning the topology may be performed semi-automatically, where theconferee is requested to look on a certain location on the screen and topoint with a cursor on an organ on the image of the conferee's face,putting the cursor on an eye, the nose, etc.

At the end of the learning period, a decision may be made in block 510whether the conference is running The conference may be considered asrunning when the video image presented over the screen of the firstendpoint is received from at least one other site. If not running,process 500 waits until the conference begins to run. If in block 510the conference is running, then information on the current presentedlayout on the first screen is obtained in block 512 from CSC 442. Theinformation may include the coordinates of the top left and bottom rightof each segment, the coordinates, in pixels (Wc;Hc), of the center ofeach segment, the number of cameras in the site of that segment, etc.The CPOVD 453, which is associated with the input module 451 that isassigned to the first endpoint, may obtain a decoded video stream thatwas received from the center camera of the first endpoint in order todetect in block 512 the gaze of the first conferee.

Detecting the gaze may be done by one or more of the techniques that aredescribed above. The gazing point on the screen of the first endpointmay be expressed in pixels (Wg;Hg) from the top left corner of thescreen. Based on the coordinates of the gazing point (Wg;Hg) on thescreen of the first endpoint and the obtained information on the layoutpresent on that screen, process 500 may determine in block 512 thesegment at which the first conferee is looking Based on the informationobtained on that segment in block 504, a decision is made in block 520whether the remote site (the site that is presented in that observedsegment) has a single camera. If so, process 500 waits in block 540 fora predetermined period of time. The predetermined period of time may bea configurable period between few tens of milliseconds to few seconds,for example. After the waiting period of block 540 process 500 returnsto block 512 and starts a new cycle of adapting the presented image tothe gaze of the conferee.

If in block 520 the remote site has more than one camera, then process500 proceeds to block 522 in which the CPOVD 453 determines, based onthe detected coordinates (Wg;Hg) of the first conferee's gaze and thecoordinates of the center of the relevant segment (Wc;Hc), whether thefirst conferee looks at the center of the segment, the left side, or theright side of the segment. In one embodiment, the decision may be madeby using two values as thresholds A1 and A2 wherein the absolute valueof A2 is larger than A1. The values of A1 and A2 may depend on the sizeof the segment, where the bigger the segment the bigger the values of A1and A2.

In order to determine in block 522 whether the first conferee looks atthe center of the segment, a CPOVD 453 may calculate the value of(Wc−Wg). If the absolute value is smaller than A1, then CPOVD 453 maydecide that the first conferee looks at the center of the segment. Thus,the current selected camera in the remote site is the center camera 322.To determine whether the first conferee looks at the left side of thesegment, CPOVD 453 may check if Wg<(Wc−A2). If so, then CPOVD 453 maydecide that the first conferee looks at the left side of the segment andthe right camera 324 may be selected to match the gaze. In order todetermine whether the first conferee looks at the right side of thesegment, CPOVD 453 may check if Wg>(Wc+A2). If so, then CPOVD 453 maydecide that the first conferee looks at the right side of the segment.Thus, the current selected camera in the remote site is the left camera324.

The CPOVD 453 may then determine whether there is a need to switch fromthe previous selected camera to the current selected camera. If in block530 the previous selected camera is the same as the current selectedcamera, then there is no need to switch cameras and process 500continues to block 540. The decisions may be established according tovarious predetermined criteria, including a predefined change in theangle of the viewer's point of view, a predefined angle from which acertain camera's input is to be chosen; etc. If there is a need toswitch cameras, then an instruction may be sent in block 532 to theeditor module 456 to start the transition from the video stream receivedfrom the previous selected camera to the video stream received from thecurrent selected camera. The instruction may be sent via the CSC 442.After instructing the editor 456, process 500 may wait in block 540before starting a new cycle from block 512.

In one embodiment of method 500, block 522 may further consider whetherthe video image of the transmitting endpoint was cropped along the widthaxis before being placed in the segment of the CP layout. If it was, theCSC 442 may check if the cropping area can be slightly moved in thedirection that leads the Wg toward the We of the segment. Only aftersliding the cropped image under the segment, CPOVD 453 may thendetermine whether there is a need to switch from the previous selectedstream (camera) of the transmitting endpoint to the current selectedstream (camera of the transmitting endpoint).

Although the description above is written in terms of selecting acamera, one skilled in the art will recognize that a selection of acamera may be accomplished by selecting a video stream that is generatedby the camera. Therefore, the terms selecting a video stream andselecting a camera may be considered as interchangeable terms.

It is to be understood that the above description is intended to beillustrative, and not restrictive. The above-described apparatus,systems, and methods may be varied in many ways, including, changing theorder of steps, and the exact implementation used. The describedembodiments include different features, not all of which are required inall embodiments of the present disclosure. Moreover, some embodiments ofthe present disclosure use only some of the features or possiblecombinations of the features. Different combinations of features notedin the described embodiments will occur to a person skilled in the art.Furthermore, some embodiments of the present disclosure may beimplemented by combination of features and elements that have beendescribed in association to different exemplary embodiments along thediscloser. The scope of the invention is limited only by the followingclaims and equivalents thereof.

What is claimed is:
 1. A continuous presence videoconferencing apparatus, comprising: a conferee point-of-view detector that determines a gaze of a first conferee relative to a video display associated with the first conferee; and a video editor, communicatively coupled to the conferee point-of-view detector, that builds a continuous presence video image from a video stream selected from a plurality of video streams responsive to the gaze of the first conferee.
 2. The continuous presence videoconferencing apparatus of claim 1, further comprising: a video camera positioned with the video display, coupled to the conferee point-of-view detector, configured to image the first conferee, wherein the conferee point-of-view detector is configured to obtain a video image of the first conferee from the video camera; and determine the gaze of the first conferee relative to the obtained video image.
 3. The continuous presence videoconferencing apparatus of claim 1, further comprising: a control module coupled to the conferee point-of-view detector, configured to design a continuous presence videoconferencing layout, and to provide information to the conferee point-of-view detector on each segment of the continuous presence videoconferencing layout.
 4. The continuous presence videoconferencing apparatus of claim 1, wherein the conferee point-of-view detector is configured to detect the gaze of the first conferee on a continuous presence video image that is presented on the video display; determine a segment of the continuous presence video image at which the first conferee is looking; and select a video stream from a plurality of video streams corresponding to the segment.
 5. The continuous presence videoconferencing apparatus of claim 4, wherein the plurality of video streams were obtained from three cameras corresponding to the segment.
 6. The continuous presence videoconferencing apparatus of claim 1, wherein the conferee point-of-view detector determines a gaze of the first conferee as an angle relative to a perpendicular orientation to the video display.
 7. The continuous presence videoconferencing apparatus of claim 1, wherein the conferee point-of-view detector determines a gaze of the first conferee as a two-dimensional pixel count relative to a predetermined position on the continuous presence video image.
 8. The continuous presence videoconferencing apparatus of claim 1, wherein the conferee point-of-view detector is contained in an input module of a multipoint control unit.
 9. The continuous presence videoconferencing apparatus of claim 1, wherein the conferee point-of-view detector is contained in a video module of a multipoint control unit.
 10. A method of building a continuous presence video image, comprising: determining a gaze of a first conferee relative to a video display associated with the first conferee; receiving a plurality of video streams; selecting a video stream of the plurality of video streams responsive to the gaze of the first conferee; and building a continuous presence video image from the selected video stream.
 11. The method of claim 10, wherein the act of determining a gaze of a first conferee relative to a video display associated with the first conferee comprises: receiving a video image from a video camera positioned with the video display; and determining the gaze of the first conferee relative to the video image.
 12. The method of claim 10, wherein the act of determining a gaze of a first conferee relative to a video display associated with the first conferee comprises: determining which of a plurality of segments of a continuous presence layout is looked at by the first conferee; and determining which camera of an endpoint corresponding to the segment of the plurality of segments looked at by the first conferee corresponds to a direction of the first conferee's gaze.
 13. The method of claim 10, further comprising: detecting a change in the gaze of the first conferee; selecting a different video stream of the plurality of video streams responsive to the change in the gaze of the first conferee; and building a continuous presence video image using the different video stream.
 14. The method of claim 13, wherein the act of detecting a change in the gaze of the first conferee is performed periodically.
 15. The method of claim 13, wherein the act of selecting a different video stream of the plurality of video streams responsive to the change in the gaze of the first conferee comprises: determining whether the change in gaze of the first conferee meets a predetermined criteria; and not selecting a different video stream if the change in gaze of the first conferee does not meet the predetermined criteria.
 16. The method of claim 13, wherein the act of building a continuous presence video stream using the different video stream comprises: smoothing a transition between a first continuous presence video image and a second continuous presence video image.
 17. The method of claim 10, wherein the act of determining a gaze of a first conferee relative to a video display associated with the first conferee comprises: learning a topology of a first site corresponding to the first conferee.
 18. The method of claim 17, wherein the act of learning a topology of a first site corresponding to the first conferee comprises: prompting the first conferee to look at a plurality of locations on a video display associated with the first site; and identifying the gaze of the first conferee at each of the plurality of locations.
 19. A continuous presence videoconferencing system, comprising: a conferee point-of-view detector, configured to determine a gaze of a conferee and to generate a gaze information; a camera selector controller, configured to receive the gaze information; and select a video stream of a plurality of video streams received from a transmitting endpoint responsive to the gaze information.
 20. The continuous presence videoconferencing system of claim 19, wherein the conferee point-of-view detector is contained in an endpoint, and wherein the camera selector controller is contained in a multipoint control unit communicatively coupled to the endpoint.
 21. The continuous presence videoconferencing system of claim 19, wherein the conferee point-of-view detector and the camera selector controller are contained in an endpoint.
 22. The continuous presence videoconferencing system of claim 19, further comprising: a video editor, configured to update a video image in a segment of a continuous presence layout responsive to selection of a video stream by the camera selector controller.
 23. The continuous presence videoconferencing system of claim 19, further comprising: a plurality of video editors, each configured to update a video image in a segment of a continuous presence layout responsive to a selection of a video stream by the camera selector controller.
 24. The continuous presence videoconferencing system of claim 19, further comprising: a plurality of camera selector controllers, each configured to receive the gaze information for a conferee at an endpoint of a plurality of endpoints; and a plurality of video editors, each coupled to one of the plurality of camera selector controllers and configured to update a video image in a segment of a continuous presence layout responsive to a selection of a video stream by the corresponding camera selector controller. 